Update m-site-plugin to 3.9.1 and use Fluido Skin 1.9

diff --git a/pom.xml b/pom.xml
index 34b519f..93bbc87 100644
--- a/pom.xml
+++ b/pom.xml
@@ -123,5 +123,27 @@
       <scope>test</scope>
     </dependency>
   </dependencies>
-
+  <build>
+    <pluginManagement>
+      <plugins>
+        <!-- remove with next parent upgrade -->
+        <plugin>
+          <artifactId>maven-project-info-reports-plugin</artifactId>
+          <version>3.1.1</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-enforcer-plugin</artifactId>
+          <version>3.0.0-M3</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-javadoc-plugin</artifactId>
+          <version>3.2.0</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-site-plugin</artifactId>
+          <version>3.9.1</version>
+        </plugin>
+      </plugins>
+    </pluginManagement>
+  </build>
 </project>
diff --git a/src/site/site.xml b/src/site/site.xml
index 7db168f..3293ef7 100644
--- a/src/site/site.xml
+++ b/src/site/site.xml
@@ -19,7 +19,13 @@
 under the License.
 -->
 
-<project xmlns="http://maven.apache.org/DECORATION/1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/DECORATION/1.0.0 http://maven.apache.org/xsd/decoration-1.0.0.xsd">
+<project xmlns="http://maven.apache.org/DECORATION/1.8.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/DECORATION/1.8.0 https://maven.apache.org/xsd/decoration-1.8.0.xsd">
+  <skin>
+    <groupId>org.apache.maven.skins</groupId>
+    <artifactId>maven-fluido-skin</artifactId>
+    <version>1.9</version>
+  </skin>
   <body>
     <menu name="Overview">
       <item name="Introduction" href="index.html"/>
@@ -27,7 +33,7 @@
       <item name="Source Xref" href="xref/index.html"/>
       <!--item name="FAQ" href="faq.html"/-->
       <!-- According to https://issues.apache.org/jira/browse/MNGSITE-152 -->
-      <item name="License" href="http://www.apache.org/licenses/"/>
+      <item name="License" href="https://www.apache.org/licenses/"/>
       <item name="Download" href="download.html"/>
     </menu>